I recently purchased a 17 piece of Cuisinart Chef's Classic Stainless clad cookware and am very unhappy with it. Virtually all the pieces now have an oxidadized inner bottom.

Does this occur to all your stainless steel pans or only the Cuisinart? Is it oxidation (rust) or a white substance that has cemented itself onto the base of the pan? When you say it cannot be removed - what have you tried? I suggest Barkeeper's Friend and a soft sponge. If Barkeeper's Friend does not remove it, then there is something wrong. We can try to narrow down what it is once we find out a little more info.

A few years ago I bought a hand-hammered unlined copper pot at a fair in Buenos Aires (I know - I have a good life). I have cooked caramel in it only a few times because there was a very metallic taste. I feel like this pan could be fantastic, as I saw many people street venders cooking candied nuts in it on the streets, but I am a little nervous about using it. I can find hardly any information about cooking with unlined copper on the web, and was hoping maybe someone here had some advice. Should I avoid it, can I pre-wash it with something, or should I search out a place to get it lined with tin? Thanks for any ideas people have.

A really first rate article. This is the clearest, best researched article about the properties of various materials in cookware!! Thank you! I must say though that my favorite pan is my carbon steel French omelette pan. Julia Child mentioned in her book that one of the great French chefs used only carbon steel for omelettes. I thought that was enough of a recommendation to try it. My pan is a 2 mm thick 24 cm blued Lyonnaise shaped pan made by De Buyer. I've been using it for a month and I can say that I love it. (I've cooked so many eggs in the last month that my wife thinks I'm addicted)

The review of the metal properties is pretty spot on, but the point of carbon steel isn't thermal properties, it's surface properties. You have to use some type of fat with eggs (I used clarified butter), but the result is as close to non-stick as you can get with a surface that tolerates metal utensils and will last forever. Oh yeah, and this gourmet pan costs under $40.

A 2mm pan is heavy enough to have thermal properties that is not quite as good as a thicker cast iron, but pretty darn close. Yet it is lighter, slick and makes perfect eggs. There might be other pans that can perform just as well, but none that will last 3 lifetimes and only cost $30-40.

You explain the science but that is just the "cause" and we need to know the "effect." For the thermal conductivity you mention practical examples such as hot spots and have those great images, but you haven't given practical examples for the heat capacity or diffusion parts. So what happens if I put a big steak onto a material with high heat capacity versus one with low?

Also you never talked about the transmission of heat from the cooking material to the food. Does that just mirror thermal conductivity of the fire to the cooking material? In other words if I have two almost identical pans made of magic materials where the only difference is that pan A has a low thermal conductivity while pan B has a high thermal conductivity, what would happen differently if I heated both pans up to 300 degrees F and put a big steak on each?

You say that aluminum and copper are the best "in terms of both holding and dishing out energy" because of their high thermal diffusion values.

But as you said
thermal diffusivity = thermal conductivity / (density and specific heat)

So if specific heat goes up then thermal diffusivity goes down. But specific heat is the ability to "hold energy." So then how can you say that a high thermal diffusivity means that a material can hold energy well?

So what happens if I put a big steak onto a material with high heat capacity versus one with low?

In these idealized examples, two identical pans except one with low thermal conductivity (A) and one with high thermal conductivity (B):
A has a lower thermal diffusivity than B. Because heat capacitance is the same, both pans have the same amount of thermal energy to potentially contribute to the food, but A will cook slower than B. The steak will take longer to brown and cook through on A than B. The closest example I can come up with in the real world is a stainless steel (A) vs cast iron (B) pan, but it would have to be an exceptionally thick stainless steel pan or an exceptionally thin cast iron pan in order for the non-thermal conductivity variables to be somewhat similar. Usually, a cast iron pan has much more material volume (and thus total heat capacitance) than a stainless steel pan, so that makes this example a bit useless unless one can fine a sheet of stainless steel thick enough to match the heat capacitance of a cast iron pot...

In the second scenario (differing heat capacities) - this is actually one where a real world example could come into play. For the same material - let's do stainless steel - we have pans of different thickness. Thermal diffusivity of the pans are identical since the material has not changed, but heat capacity is higher on the thick pan because it has a larger volume of material and heat capacity = specific heat * specific gravity * volume of material. What happens when you stick a big steak on the thin pan and the thick pan is that cooking occurs at the same rate (same thermal diffusivity), but the pan with less heat capacity will "run out of energy" sooner than the other pan. If no additional heat is applied to the system, then it will stop cooking before the thicker pan. Considering the situation that heat (the burner) is added to the system, complicates matters a bit, but the end result is somewhat similar. The thinner pan will initially cook the same as the thick pan, but hot spots will form sooner than the thick pan as it begins to run out the energy that was initially stored in the pan and heating comes mainly from conduction from the burner through the pan material. The thicker pan will eventually reach this point, but the process will be a little slower as there is more of a "buffer".

So if specific heat goes up then thermal diffusivity goes down. But specific heat is the ability to "hold energy." So then how can you say that a high thermal diffusivity means that a material can hold energy well?

Yeah, that sentence is misleading. High thermal diffusivity means that the material can react to temperature changes rapidly (thus shedding or dishing out the energy stored in it rapidly), but it is heat capacity that determines how much it holds (like you said). It just so happens that in the small group of materials we examine in the article, they all have relatively high heat capacities. I'll think of a way to reword (or drop) that misleading statement.

Hey, brilliantly written atricle, but I have a question : Cooking spoons are also termed along with every other cookware as cooking utensils, right?
So, if we talk about cooking spoons then its material should have low thermal conductivity and high specific heat capacity, right? So that the spoon doesn't get too heated up too easily during cooking.
So my question is: Which one of the following should be the properties of cooking utensils?
a) High specific heat and low conductivity.
b) Low specific heat and high conductivity.
We can't chose (a) because pans and pots should have high conductivity and low specific heat and we can't chose (b) because cooking utensils are also spoons so then cooking spoons shouldn't have high conductivity and low specific heat.
But I have to choose an answer, this is a very important college exam MCQ, what should I do?
I hope someone answers, I'll be waiting!

So, if we talk about cooking spoons then its material should have low thermal conductivity and high specific heat capacity, right? So that the spoon doesn't get too heated up too easily during cooking.
So my question is: Which one of the following should be the properties of cooking utensils?
a) High specific heat and low conductivity.
b) Low specific heat and high conductivity.
We can't chose (a) because pans and pots should have high conductivity and low specific heat and we can't chose (b) because cooking utensils are also spoons so then cooking spoons shouldn't have high conductivity and low specific heat.

I think this comes down to definition. What is meant by "cooking utensil"? I usually think of utensils as separate from cookware (pots/pans) so I'm thinking spatulas, spoons, stirring sticks, etc. But I understand there are parts of the country and world that call everything a cooking utensil. In that case, it's a stupid question since a spoon and a pot serves two completely different purposes - so how can the question be answered correctly?

Posted: Tue May 03, 2011 1:34 pm Post subject: just what I was looking for in cookwear material comparison

Thanks so much for this very thorough explanation. It was exactly what I was looking for with the perfect mix of details and explanation. Again, thank you for takign the time to due the work and post it on the web. One engineer to another: Well done!

I wonder how titanium fits in to the picture, I know it's a poor conductor but boil tests online show it being as good as aluminium - not possible surely?

Titanium's thermal properties are similar to stainless steel, but titanium is much stronger and most titanium cookware (designed for the camping and backpacking community) is extremely thin. In fact, when compared to equivalent aluminum camping cookware, the heating surface of the titanium pot is thin enough to produce similar heating times as that of aluminum (important when trying to conserve fuel). The big downside with such a thin pot? Hot spots. But, when camping heating food quickly in light cookware is more important than heating food evenly.

P.S. There is a little more to it than just a thin base - the thickness of the sides walls and rim of the pot can have an effect on water heating times because while the water is heating, the sides of the cookware are also heating. Aluminum will dissipate that heat faster than titanium, so boiling a completely full pot will probably be more advantageous to the aluminum cookware vs the titanium. (A half full pot will essentially have a tall ring of metal above the surface of the water acting as a radiator which will slow down the boil time. The efficiency of that radiator will depend on the design, mass, thickness, and material of the sides of the pot.)